Apparatus and method for manufacturing an automotive beam

ABSTRACT

The present invention concerns an apparatus and method for manufacturing an automotive beam for use as a beam in structural components of automobiles with significant improvements in terms of torsional rigidity and yield strength. The beam improves the overall safety of passengers and maintains the simplicity of the manufacturing process. The apparatus ( 1 ) for manufacturing roll formed profile beams comprises a plurality of material dispensers ( 2,6 ), a first set of rollers ( 5 ), a second set of rollers ( 11 ), a first welding station ( 10 ) mounted between the two sets of rollers ( 5, 11 ) and a second welding station ( 12 ) at the outlet of the second set of rollers ( 11 ). The method of manufacturing roll formed profile beams comprises the steps of roll forming a first profile element followed by roll forming a second profile element enclosing the first profile element and forming a closed profile beam having an internal support structure.

[0001] The present invention relates to an apparatus and method formanufacturing an automotive beam and in particular to an apparatus andmethod for roll forming a closed profile beam.

[0002] Beams used on the body structure of an automobile and beamsmounted at the front and rear of automobiles are required to absorbimpact from collisions with other vehicles and with other objects. Beamsmanufactured for these purposes need to have a high resistance totorsion and good strength characteristics in order to prevent localbuckling of the beam. A number of prior art patent and patentapplication specifications have disclosed beams for use in theautomotive industry and apparatuses and methods for manufacturing suchbeams.

[0003] U.S. Pat. No. 5,934,544 provides an apparatus and method formanufacturing automotive bumper beams by a single roll forming process.The apparatus includes an uncoiler, a straightner, a group of rollformers, a sweep roll former, a welding member and a cutting member. Themethod of manufacturing the bumper beam includes preparing the sheetmetal, forming the cross sectional profile, forming a sweep, adjustingthe tubular cross sectional shape of the sheet metal and welding thesheet metal prior to cutting the beam into desired lengths. The objectsof the invention are to provide a beam with strengthened impactresistance, reduced weight and to simplify the manufacturing processesof the prior art.

[0004] International Patent Application No. PCT/SE97/00305 discloses avehicle body comprising a beam structure consisting of thin-walledflange-free profile parts with closed cross sections made by means ofroll forming. The component parts of the beam structure are hardened sothat the boron steel or other high tensile steel has a yield limit ofthe order of 900-1100 MPa. The object of the invention is to produce anew and lighter type of vehicle body with an increased body strength andstiffness.

[0005] In order to maintain an efficient manufacturing process for beamsit is important to use a production line technique manufacturing beamsin a relatively small number of steps while maintaining their structuralintegrity and safety characteristics. The safety and structuralintegrity aspects are particularly important when the beams aremanufactured for use as protective members in an automobile. Althoughthe techniques disclosed in the above referenced specifications maintainan efficient manufacturing process and address the issues of improvedstrength characteristics and weight of the beam, significantimprovements could still be made regarding the safety aspects of beamsfor use in automobiles which would inevitably result in improvements tohuman safety.

[0006] It is an object of the present invention to provide a beam foruse in structural components of automobiles with significantimprovements in terms of torsional rigidity and yield strength toimprove the overall safety of passengers travelling in such automobilesin addition to maintaining the simplicity of the manufacturing process.

[0007] The present invention provides an apparatus for manufacturingroll formed profile beams characterised in that the apparatus comprisesa plurality of material dispensers, a first set of rollers and a secondset of rollers and a first welding station mounted between and being incommunication with the two sets of rollers and a second welding stationin communication with the outlet of the second set of rollers, whereinone dispenser is in communication with the inlet of the first set ofrollers and another dispenser is in communication with the inlet of thefirst welding station.

[0008] Preferably, the material dispensers are provided by uncoilerseach carrying a coil of sheet material.

[0009] Ideally, the sheets are manufactured from high strength steel.Steel provides the desired characteristics for beams to be used in theautomotive industry as impact absorbers.

[0010] In one embodiment, the sheets are made from the same steel.

[0011] In another embodiment, the sheets are manufactured from differentsteels. This allows the manufacturer greater flexibility and allows forthe manufacture of beams of different strength characteristics dependingon their specified end-use.

[0012] In a particularly preferred embodiment, the sheet material isboron steel. Hardened boron steel has a yield limit of the order of900-1100 MPa and is a particularly suitable for beams used in theautomotive industry.

[0013] Although the present invention describes a preferred embodimentutilising steel and in particular high strength boron steel, it will ofcourse be appreciated that other steels or metal alloys providingdesired characteristics regarding torsional rigidity and strength couldalso be used.

[0014] In one embodiment, the sheets of material have the samethickness.

[0015] In another embodiment, the sheets of material have differentthicknesses. Again this provides flexibility for the manufacturer andthe end user.

[0016] In a further aspect of the invention, the sheet material definespre-punched apertures at predefined locations. Both sheet materials oronly one sheet may be pre-punched which results in a reduction of weightto the overall beam structure. Additionally, the pre-punched holes mayact as ventilation for the beam during the heat treatment procedures.

[0017] An apparatus for manufacturing roll formed closed profile beamscomprising a first dispenser carrying a roll of sheet material, a firstgroup of rollers for forming the sheet into a predefined profile incommunication with both the first dispenser and a first welding station,a second dispenser carrying a second roll of sheet material incommunication with a first welding station, wherein the first weldingstation welds the profile element formed by the first group of rollersonto a predefined location on the sheet fed from the second dispenser, asecond group of rollers for receiving the newly welded profile elementand sheet from the first welding station and for forming the sheetaround the first formed profile element by bringing the longitudinalfree edges of the sheet to a meeting point enclosing the first profileelement and a second welding station for welding the longitudinal freeedges together with a surface of the first profile element to form aclosed profile beam having an internal support structure.

[0018] The present invention also provides a method of manufacturingroll formed profile beams characterised in that the method comprises thesteps of roll forming a first profile element followed by roll forming asecond profile element enclosing the first profile element and forming aclosed profile beam having an internal support structure.

[0019] Ideally, the first profile element is formed as an internalsupport profile.

[0020] In one embodiment, the profile element is substantially U-shapedhaving a base and a pair of legs extending substantially perpendicularlyfrom the base in the same direction as one another.

[0021] In a further embodiment, the legs of the profile element includeribs. The ribs improve the strength of the profile element.

[0022] Ideally, the internal support profile element is welded to asecond sheet material at a welding station.

[0023] Preferably, the second sheet material is subsequently roll formedinto a beam enclosing the first profile element.

[0024] Ideally, the second profile element is closed around the firstprofile element by welding the longitudinal ends of the second profileelement together with a portion of the first profile element.

[0025] Ideally, the first profile element is welded to the second sheetby means of seam welding.

[0026] Preferably, the two longitudinal edges of the second profileelement are laser welded together with a portion of the second profileelement.

[0027] A method for forming closed profile beams comprising the stepsof;

[0028] dispensing a first sheet from a first dispenser to a first set ofrollers, forming the sheet to a predefined profile and feeding theprofile element to a first welding station, dispensing a second sheetfrom a second dispenser to the first welding station, welding theprofile element to the second sheet at the first welding station,feeding the newly formed sheet and profile element to a second set ofrollers, forming the sheet by bringing the free longitudinal edges ofsaid sheet to a meeting point thereby enclosing the first profileelement feeding the workpiece to a second welding station and weldingthe longitudinal free edges of the second sheet together with a surfaceof the first profile element to form a closed profile beam having aninternal support structure.

[0029] The invention will now be described with reference to theaccompanying drawings, which show, by way of example only, oneembodiment of an apparatus and method for manufacturing an automotivebeam in accordance with the invention. In the drawings:—

[0030]FIG. 1 is a schematic drawing showing an elevation view of theapparatus;

[0031]FIG. 2 is an end view of a first profile element in accordancewith the invention;

[0032]FIG. 3 is an end view of a second profile element in accordancewith the invention; and

[0033]FIG. 4 is a schematic end view of the second roll forming processstep by step.

[0034] Referring to the drawings and initially to FIG. 1 there is shownan apparatus for manufacturing automotive beams indicated generally bythe reference numeral 1. A first dispenser 2 contains a coil of sheetmaterial 3 and a first sheet 4 extends from the first dispenser 2 to afirst set of forming rollers 5. A second dispenser 6 contains a secondcoil of sheet material 7 and a second sheet 8 extends from the seconddispenser 6 to a first set of support rollers 9. A first welding station10 is located between the first set of forming rollers 9 and a secondset of forming rollers 11. A second welding station 12 is mountedbetween the second set of forming rollers 11 and a second set of supportrollers 13. An induction warming oven containing two separate ovens 14and 15 is mounted either side of a third set of support rollers 16 andthe outlet of the separate oven 15 leads to a quenching station 17. Aset of stretching rollers 18 are mounted between the quenching station17 and a knife 19, which is the final station in the production lineapparatus 1.

[0035] Referring to FIG. 2 there is shown a first profile elementindicated generally by the reference numeral 21. The profile element 21is substantially U-shaped having a base 23 and a pair of legs 24extending substantially perpendicularly from the base 23 in the samedirection as one another. Each leg 24 terminates with an integrallyformed flange 25, the flanges 25 extending in opposite directions toeach other and in a plane parallel with the base 23.

[0036] Referring to FIG. 3, the second profile element 47 is shownhaving two parallel sides 51, 52 connected by two sides 53, 54 forming atubular closed profile element 47.

[0037] In FIG. 4, there is shown a step by step view of the roll formingprocess which occurs between the first welding station 10 and the secondwelding station 12 (see FIG. 1). Two weld joints 31 are shown betweenthe flanges 25 of the profile element 21 and the second sheet 8. Anumber of stages of the roll forming process from 32, in which thesecond sheet 8 is in a flat orientation, to 47 in which the second sheet8 is formed as a second profile element 47 enclosing the profile 21 areshown. A third weld joint 48 is shown between the longitudinal edges 49,50 of the sheet 8 and the base 23 of the profile element 21.

[0038] In use, a first sheet 4 extends from a first dispenser 2 to afirst set of rollers 5 which form the sheet 4 to a predefined profile.The profile element 21 is fed from the first set of rollers 5 to thefirst welding station 10. The second sheet of metal 8 is dispensed fromthe second dispenser 6 to the first welding station 10 via the first setof support rollers 9. The profile element 21 is welded to the secondsheet of metal 8 at the first welding station 10. The newly combinedprofile element 21 and sheet 8 is fed to the second set of rollers 11which form the sheet 8 by bringing the free longitudinal edges 49, 50 ofthe second sheet of metal 8 to a meeting point thereby enclosing thefirst profile element 21. The forming process is completed when thework-piece is fed to a second welding station 12 and the longitudinalfree edges 49, 50 of the second sheet 8 are welded together with thebase 23 of the first profile element 21 to form a closed profile beamhaving an internal support structure.

[0039] It will of course be understood that the invention is not limitedto the specific details as herein described, which are given by way ofexample only, and that various alterations and modifications may be madewithout departing from the scope of the invention as defined in theappended claims.

1. An apparatus (1) for manufacturing roll formed profile beamscharacterised in that the apparatus comprises a plurality of materialdispensers (2, 6), a first set of rollers (5) and a second set ofrollers (11) and a first welding station (10) mounted between and beingin communication with the two sets of rollers (5, 11) and a secondwelding station (12) in communication with the outlet of the second setof rollers (11), wherein one dispenser is in communication with theinlet of the first set of rollers (5) and another dispenser is incommunication with the inlet of the second welding station (12).
 2. Anapparatus as claimed in claim 1, wherein the material dispensers (2, 6)are provided by uncoilers each carrying a coil of sheet material (3, 7).3. An apparatus as claimed in claim 2, wherein the sheets (3, 7) aremanufactured from high strength steel.
 4. An apparatus as claimed inclaim 3, wherein the sheets (3, 7) are made from the same steel.
 5. Anapparatus as claimed in claim 3, wherein the sheets (3, 7) aremanufactured from different steels.
 6. An apparatus as claimed in any ofclaims 3 to 5, wherein the steel is boron steel.
 7. An apparatus asclaimed in any of claims 2 to 6, wherein the sheets (3, 7) have the samethickness.
 8. An apparatus as claimed in any of claims 2 to 6, whereinthe sheets (3, 7) have different thicknesses.
 9. An apparatus as claimedin any of claims 2 to 8, wherein both of the sheet materials definepre-punched apertures at predefined locations.
 10. An apparatus asclaimed in claim 9, wherein only one sheet defines pre-punchedapertures.
 11. A method of manufacturing roll formed profile beamscharacterised in that the method comprises the steps of roll forming afirst profile element (21) followed by roll forming a second profileelement (47) which encloses the first profile element (21) to form aclosed profile beam.
 12. A method as claimed in claim 11, wherein thefirst profile element (21) is formed as an internal support profile. 13.A method as claimed in any of claims 11 to 12, wherein the first profileelement (21) is substantially U-shaped.
 14. A method as claimed in claim13, wherein legs (24) of the U-shaped profile element (21) include ribs.15. A method as claimed in any of claims 11 to 14, wherein the profile(21) is welded to a second sheet (8) at a welding station (10).
 16. Amethod as claimed in claim 15, wherein the second sheet (8) issubsequently roll formed into a beam (47) enclosing the first profileelement (21).
 17. A method as claimed in any of claims 12 to 16, whereinlongitudinal edges (49, 50) of the second profile element (47) arewelded together with a portion of the first profile element (21) therebyenclosing the first profile element (21) within the second profileelement (47).
 18. A method as claimed in any of claims 15 to 17, whereinthe first profile element (21) is welded to the second sheet (8) bymeans of seam welding.
 19. A method as claimed in claim 17, wherein thetwo longitudinal edges (49, 50) of the second profile element (47) arelaser welded together with a portion of the first profile element (21).